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crypto: sun4i-ss - Remove insecure and unused rng_alg

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Remove sun4i_ss_rng, as it is insecure and unused:

- It has multiple vulnerabilities.  sun4i_ss_prng_seed() is missing
  locking and has a buffer overflow.  sun4i_ss_prng_generate() fails to
  fill the entire buffer with cryptographic random bytes, because it
  rounds the destination length down and also doesn't actually wait for
  the hardware to be ready before pulling bytes from it.

- No user of this code is known.  It's usable only theoretically via the
  "rng" algorithm type of AF_ALG.  But userspace actually just uses the
  actual Linux RNG (/dev/random etc) instead.  And rng_algs don't
  contribute entropy to the actual Linux RNG either.  (This may have
  been confused with hwrng, which does contribute entropy.)

The sun4i_ss_prng_seed() buffer overflow was reported by Tianchu Chen
and discovered by Atuin - Automated Vulnerability Discovery Engine

There's no point in fixing all these vulnerabilities individually when
this is unused code, so let's just remove it.

Fixes: b8ae5c7387 ("crypto: sun4i-ss - support the Security System PRNG")
Cc: stable@vger.kernel.org
Reported-by: Tianchu Chen <flynnnchen@tencent.com>
Closes: https://lore.kernel.org/r/af749a8447bd7f0e9dd26ca6c87e9c6afecb09d9@linux.dev/
Acked-by: Corentin LABBE <clabbe.montjoie@gmail.com>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers
2026-06-01 16:07:57 +00:00
committed by Herbert Xu
parent be6498ca1c
commit b2c41fa9dd
6 changed files with 0 additions and 143 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
arch/arm/configs/sunxi_defconfig
View File

@@ -170,7 +170,6 @@ CONFIG_ROOT_NFS=y
CONFIG_NLS_CODEPAGE_437=y
CONFIG_NLS_ISO8859_1=y
CONFIG_CRYPTO_DEV_SUN4I_SS=y
CONFIG_CRYPTO_DEV_SUN4I_SS_PRNG=y
CONFIG_CRYPTO_DEV_SUN8I_CE=y
CONFIG_CRYPTO_DEV_SUN8I_SS=y
CONFIG_DMA_CMA=y

8
drivers/crypto/allwinner/Kconfig
View File

@@ -24,14 +24,6 @@ config CRYPTO_DEV_SUN4I_SS
To compile this driver as a module, choose M here: the module
will be called sun4i-ss.
config CRYPTO_DEV_SUN4I_SS_PRNG
bool "Support for Allwinner Security System PRNG"
depends on CRYPTO_DEV_SUN4I_SS
select CRYPTO_RNG
help
Select this option if you want to provide kernel-side support for
the Pseudo-Random Number Generator found in the Security System.
config CRYPTO_DEV_SUN4I_SS_DEBUG
bool "Enable sun4i-ss stats"
depends on CRYPTO_DEV_SUN4I_SS

1
drivers/crypto/allwinner/sun4i-ss/Makefile
View File

@@ -1,4 +1,3 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_CRYPTO_DEV_SUN4I_SS) += sun4i-ss.o
sun4i-ss-y += sun4i-ss-core.o sun4i-ss-hash.o sun4i-ss-cipher.o
sun4i-ss-$(CONFIG_CRYPTO_DEV_SUN4I_SS_PRNG) += sun4i-ss-prng.o

44
drivers/crypto/allwinner/sun4i-ss/sun4i-ss-core.c
View File

@@ -213,23 +213,6 @@ static struct sun4i_ss_alg_template ss_algs[] = {
}
}
},
#ifdef CONFIG_CRYPTO_DEV_SUN4I_SS_PRNG
{
.type = CRYPTO_ALG_TYPE_RNG,
.alg.rng = {
.base = {
.cra_name = "stdrng",
.cra_driver_name = "sun4i_ss_rng",
.cra_priority = 300,
.cra_ctxsize = 0,
.cra_module = THIS_MODULE,
},
.generate = sun4i_ss_prng_generate,
.seed = sun4i_ss_prng_seed,
.seedsize = SS_SEED_LEN / BITS_PER_BYTE,
}
},
#endif
};
static int sun4i_ss_debugfs_show(struct seq_file *seq, void *v)
@@ -247,14 +230,6 @@ static int sun4i_ss_debugfs_show(struct seq_file *seq, void *v)
ss_algs[i].stat_req, ss_algs[i].stat_opti, ss_algs[i].stat_fb,
ss_algs[i].stat_bytes);
break;
#ifdef CONFIG_CRYPTO_DEV_SUN4I_SS_PRNG
case CRYPTO_ALG_TYPE_RNG:
seq_printf(seq, "%s %s reqs=%lu tsize=%lu\n",
ss_algs[i].alg.rng.base.cra_driver_name,
ss_algs[i].alg.rng.base.cra_name,
ss_algs[i].stat_req, ss_algs[i].stat_bytes);
break;
#endif
case CRYPTO_ALG_TYPE_AHASH:
seq_printf(seq, "%s %s reqs=%lu\n",
ss_algs[i].alg.hash.halg.base.cra_driver_name,
@@ -473,15 +448,6 @@ static int sun4i_ss_probe(struct platform_device *pdev)
goto error_alg;
}
break;
#ifdef CONFIG_CRYPTO_DEV_SUN4I_SS_PRNG
case CRYPTO_ALG_TYPE_RNG:
err = crypto_register_rng(&ss_algs[i].alg.rng);
if (err) {
dev_err(ss->dev, "Fail to register %s\n",
ss_algs[i].alg.rng.base.cra_name);
}
break;
#endif
}
}
@@ -501,11 +467,6 @@ static int sun4i_ss_probe(struct platform_device *pdev)
case CRYPTO_ALG_TYPE_AHASH:
crypto_unregister_ahash(&ss_algs[i].alg.hash);
break;
#ifdef CONFIG_CRYPTO_DEV_SUN4I_SS_PRNG
case CRYPTO_ALG_TYPE_RNG:
crypto_unregister_rng(&ss_algs[i].alg.rng);
break;
#endif
}
}
error_pm:
@@ -526,11 +487,6 @@ static void sun4i_ss_remove(struct platform_device *pdev)
case CRYPTO_ALG_TYPE_AHASH:
crypto_unregister_ahash(&ss_algs[i].alg.hash);
break;
#ifdef CONFIG_CRYPTO_DEV_SUN4I_SS_PRNG
case CRYPTO_ALG_TYPE_RNG:
crypto_unregister_rng(&ss_algs[i].alg.rng);
break;
#endif
}
}

69
drivers/crypto/allwinner/sun4i-ss/sun4i-ss-prng.c
View File

@@ -1,69 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-or-later
#include "sun4i-ss.h"
int sun4i_ss_prng_seed(struct crypto_rng *tfm, const u8 *seed,
unsigned int slen)
{
struct sun4i_ss_alg_template *algt;
struct rng_alg *alg = crypto_rng_alg(tfm);
algt = container_of(alg, struct sun4i_ss_alg_template, alg.rng);
memcpy(algt->ss->seed, seed, slen);
return 0;
}
int sun4i_ss_prng_generate(struct crypto_rng *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int dlen)
{
struct sun4i_ss_alg_template *algt;
struct rng_alg *alg = crypto_rng_alg(tfm);
int i, err;
u32 v;
u32 *data = (u32 *)dst;
const u32 mode = SS_OP_PRNG | SS_PRNG_CONTINUE | SS_ENABLED;
size_t len;
struct sun4i_ss_ctx *ss;
unsigned int todo = (dlen / 4) * 4;
algt = container_of(alg, struct sun4i_ss_alg_template, alg.rng);
ss = algt->ss;
err = pm_runtime_resume_and_get(ss->dev);
if (err < 0)
return err;
if (IS_ENABLED(CONFIG_CRYPTO_DEV_SUN4I_SS_DEBUG)) {
algt->stat_req++;
algt->stat_bytes += todo;
}
spin_lock_bh(&ss->slock);
writel(mode, ss->base + SS_CTL);
while (todo > 0) {
/* write the seed */
for (i = 0; i < SS_SEED_LEN / BITS_PER_LONG; i++)
writel(ss->seed[i], ss->base + SS_KEY0 + i * 4);
/* Read the random data */
len = min_t(size_t, SS_DATA_LEN / BITS_PER_BYTE, todo);
readsl(ss->base + SS_TXFIFO, data, len / 4);
data += len / 4;
todo -= len;
/* Update the seed */
for (i = 0; i < SS_SEED_LEN / BITS_PER_LONG; i++) {
v = readl(ss->base + SS_KEY0 + i * 4);
ss->seed[i] = v;
}
}
writel(0, ss->base + SS_CTL);
spin_unlock_bh(&ss->slock);
pm_runtime_put(ss->dev);
return 0;
}

20
drivers/crypto/allwinner/sun4i-ss/sun4i-ss.h
View File

@@ -31,8 +31,6 @@
#include <crypto/internal/skcipher.h>
#include <crypto/aes.h>
#include <crypto/internal/des.h>
#include <crypto/internal/rng.h>
#include <crypto/rng.h>
#define SS_CTL 0x00
#define SS_KEY0 0x04
@@ -62,10 +60,6 @@
/* SS_CTL configuration values */
/* PRNG generator mode - bit 15 */
#define SS_PRNG_ONESHOT (0 << 15)
#define SS_PRNG_CONTINUE (1 << 15)
/* IV mode for hash */
#define SS_IV_ARBITRARY (1 << 14)
@@ -94,14 +88,10 @@
#define SS_OP_3DES (2 << 4)
#define SS_OP_SHA1 (3 << 4)
#define SS_OP_MD5 (4 << 4)
#define SS_OP_PRNG (5 << 4)
/* Data end bit - bit 2 */
#define SS_DATA_END (1 << 2)
/* PRNG start bit - bit 1 */
#define SS_PRNG_START (1 << 1)
/* SS Enable bit - bit 0 */
#define SS_DISABLED (0 << 0)
#define SS_ENABLED (1 << 0)
@@ -128,9 +118,6 @@
#define SS_RXFIFO_EMP_INT_ENABLE (1 << 2)
#define SS_TXFIFO_AVA_INT_ENABLE (1 << 0)
#define SS_SEED_LEN 192
#define SS_DATA_LEN 160
/*
* struct ss_variant - Describe SS hardware variant
* @sha1_in_be: The SHA1 digest is given by SS in BE, and so need to be inverted.
@@ -151,9 +138,6 @@ struct sun4i_ss_ctx {
char buf[4 * SS_RX_MAX];/* buffer for linearize SG src */
char bufo[4 * SS_TX_MAX]; /* buffer for linearize SG dst */
spinlock_t slock; /* control the use of the device */
#ifdef CONFIG_CRYPTO_DEV_SUN4I_SS_PRNG
u32 seed[SS_SEED_LEN / BITS_PER_LONG];
#endif
struct dentry *dbgfs_dir;
struct dentry *dbgfs_stats;
};
@@ -164,7 +148,6 @@ struct sun4i_ss_alg_template {
union {
struct skcipher_alg crypto;
struct ahash_alg hash;
struct rng_alg rng;
} alg;
struct sun4i_ss_ctx *ss;
unsigned long stat_req;
@@ -231,6 +214,3 @@ int sun4i_ss_des_setkey(struct crypto_skcipher *tfm, const u8 *key,
unsigned int keylen);
int sun4i_ss_des3_setkey(struct crypto_skcipher *tfm, const u8 *key,
unsigned int keylen);
int sun4i_ss_prng_generate(struct crypto_rng *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int dlen);
int sun4i_ss_prng_seed(struct crypto_rng *tfm, const u8 *seed, unsigned int slen);